A license plate in Japan is nothing special. All plates consist of a strict sequence of characters and numbers. For example, 東京２００か１０－１０. The first Chinese character is the name of the City where it was issued. 3 random digits are followed by a Hiragana character. The sequence is completed by a four digit serial number at the end. It is very simple.
When I was living in America, I saw so many unique license plates, including plates with philosophical or religious messages on them, which I have never seen in Japan.
This starts to become a more interesting topic now because a license plate in Japan reflects part of the culture! In Japan, we do not really have a custom of showing our own messages or opinions in public. These must be hidden because harmony is the most important virtue. In fact, individualism is not really appreciated. On the other hand, in Western societies, individualism is embraced. The more different you are, the better it seems to be.
But in my opinion, I simply prefer license plates that are very simple and easy to read, like the Japanese ones. It actually improves my driving as I had almost a car accident in America when I was reading a message on a license plate in front of my car. Folks – be careful out there!